The secondary battery generally comprises an electrode assembly, a case receiving the electrode assembly and a cap plate, an electrode tab of the electrode assembly is fixed to an electrode terminal of the cap plate by welding (specifically, the electrode tab can be connected with the electrode terminal directly, and the electrode tab also can be connected with the electrode terminal via a connecting piece), then the electrode assembly is put into the case. But in an assembling process or a working process of the secondary battery, weld zones formed during welding will easily stab the electrode assembly or the electrode tab when the electrode assembly shakes, which affects the performance of the secondary battery.
In prior art, an isolating plate is generally provided between the weld zones and the electrode assembly for isolating the weld zones and the electrode assembly, but the installing process of the isolating plate is complex, and the isolating plate shakes easily during the working process of the secondary battery, so the isolating plate has poor stability and causes the failure of insulation.